The present invention relates to internal fitting systems for sport shoes in general and in particular to a novel internal fitting system for a ski boot or the like.
A conventional ski boot as presently used in downhill skiing with a ski release binding typically comprises a relatively rigid exterior lower shell member and upper cuff member and a relatively soft interior liner. The shell member and cuff member are designed to provide mechanical protection and support for a foot, ankle and lower leg and to provide a stable means for releasably securing the boot to a ski. The shell member and cuff member usually are pivotably coupled in the proximity of the ankle. Boots constructed with a pivoting cuff member generally provide restraint against excess sideways and rearward bending at the ankle while providing limited forward bending of the leg relative to the foot. Less commonly, boots are constructed without a pivoting cuff member and forward bending is restricted or accomplished by providing for a separation of the upper forward section of the cuff member.
The relatively rigid exterior lower shell member and upper cuff member in conjunction with the relatively soft interior liner should also provide restraint against upward, forward, rearward and sideways movement of the foot. This restraint is desirable to minimize foot discomfort and fatigue from recurring pressure areas and continual movement of the foot in the boot and to control the skis during various skiing maneuvers and in various terrain and snow conditions. Further, it is essential to minimize foot movement in order to maximize energy transmission between the foot and the release binding in a potential injury producing fall. In practice, the magnitude of restraint required from one moment to the next will vary as the skiing conditions and the maneuvers being executed change. Ideally, the boot should provide for a close, comfortable fit that does not compromise circulation and warmth for the tracking phase of skiing and provide for a momentary tighter fit for the turning phase of skiing and during a fall condition.
The design of conventional ski boots does not adequately compensate for the dynamic conditions that prevail in downhill skiing. With conventional boots, during a turn when skiing on packed snow, forward bending at the ankle is usually accompanied by a tendency for hindfoot upward movement and forefoot sideways movement because ski control and turning are usually accomplished by downward and sideways force applied to the forward leading edges of the skis. In powder snow, the forward leading edges are kept raised for planing on top of the snow with a tendency for forefoot upward and sideways movement. When maneuvering in snow of different consistencies or in bumpy or mogly terrain, and skier alternates, frequently and rapidly, between forward and rearward bending in the boots. As a result of this movement, ski control is significantly reduced. In most injury producing fall conditions, excess movement also reduces energy transmission between the foot and the release binding.
Because shell molds are expensive to manufacture, it is the practice to supply a limited number of shell sizes. Manufacturers then rely upon buckles with numerous and complex adjustments and liners of various configurations and constructions to provide a close, comfortable and warm fit, compensate for innumerable foot sizes and shapes, and to achieve the necessary foot restraint. However, these fitting arrangements are unsatisfactory. The use of buckles with numerous and complex adjustments usually results in a nonconforming fit. The buckle closure required to provide a close fit also usually results in uncomfortable pressure areas because of the consequent distortion of the relatively rigid shell. Additionally, conventional buckle arrangements usually do not adequately restrain the foot from sideways movement at the hindfoot and forefoot.
The use of liners of various configurations and constructions also usually results in a nonconforming fit. Because of the difficulty in supplying liner configurations that will accommodate the wide range of variation of foot sizes and shapes such as a splay or wide forefoot, wide base, angulated heel, halux valgus, boney prominences, spurs, high longitudinal arch or one foot in size variance with the other foot, liners are generally manufactured to conform to only a limited range of size and shape. Manufacturers then rely upon various liner constructions to provide a close comfortable fit. Among the constructions used there are included molded and sheet foam rubber, urethane foam, wax, cork, plastic beads, and other various flow materials. The numerous materials used is indicative of the unsatisfactory results. In spite of the above fitting arrangements, conventional boots do not provide adequate adjustment for comfort and restraint and a relatively large inventory of many shells and liner configurations and constructions is necessary to satisfy customer requirements. Moreover, a satisfactory fit in the ski shop is still often unsatisfactory on the ski slope because the foot is not necessarily fitted for skiing conditions.